Fluid distributor device for down-hole-drills

ABSTRACT

A fluid distributor device is for a percussive drill assembly including a generally tubular casing ( 2 ) having a longitudinal centerline and a piston ( 6 ) disposed within the casing so as to define a reservoir chamber ( 27 ) in the casing. The distributor device comprises a generally cylindrical body ( 12 ) disposed within the casing and including a central axis, two opposing ends spaced apart along the axis, first and second interior chambers and a port fluidly connecting the two chambers. The body further has a plurality of fluid passages extending between the two ends and fluidly connecting the first chamber with the reservoir chamber and a deflectable retainer portion ( 16 ) releasably engaged with the casing so as to retain the body at a desired position with respect to the casing centerline. A valve ( 7 ) is disposed within the body and is configured to permit fluid flow through the port and to alternatively prevent fluid flow through the port.

BACKGROUND OF THE INVENTION

The present invention relates to drill assemblies, and particularly tocomponents used to direct or distribute operating fluid within drillassemblies having one or more fluid-operated pistons.

One type of commercial drill, commonly referred to as a “down-hole”drill due to its intended application, is typically actuated by highpressure “operating” fluid (e.g., compressed air) that is appropriatelydirected in order to reciprocate a piston to repetitively impact againsta drill bit. These fluid-operated drills may be provided with one ofseveral known systems for supplying and exhausting operating fluid intoand out of specific interior fluid chambers used in the operation of thedrill. Certain fluid-actuated drills, such as those commerciallyavailable from drill manufacturers such as Sandvik, Secoroc and Numa,include a control rod device that interact with holes and ports withinthe impact piston to deliver and expel air. Other drills, such as thosecommercially available from Mission, Inc., use ports contained in theouter sleeve or casing of the drill assembly to achieve a similarresult.

A third design uses a tubular fluid distributor sleeve or “cylinder”located within the drill outer casing to define a flow path around theoperating piston, such as those commercially available from theIngersoll-Rand Company of New Jersey. More specifically, the distributorcylinder delivers high-pressure air to a first central chamber thatsupplies air to the interior working chamber(s) of the drill. Thecylinder design, while avoiding the shortcomings associated with theneed for ports in the piston or casing, does require a means forpositioning and supporting the cylinder within the casing.

Precision co-axial alignment requirements, along with holding forcesneeded to accommodate aggressive shock and vibration loads associatedwith percussive drilling, requires the supporting and positioning meansfor the cylinder to be precise, robust and reliable. Axial and radialposition must be maintained while holding forces must be large toprevent vibration, movement and resultant wear that could result inmisalignment.

Typically, a means for positioning the cylinder within the drill casingemploys a separate ring to retain the cylinder at a specified positionwithin the casing, an example of which is also disclosed in U.S. Pat.No. 5,325,926 of Lay et al. Clamping loads applied to the cylinder aretransmitted through shoulders on the cylinder, ring and into the casing.The inside shoulder of the ring carries the cylinder load and theoutside shoulder of the ring carries the casing load. Such retainingrings typically have a gap to enable the ring to “collapse” or deflectinwardly to enable the ring to be inserted within a recess in thecasing. Such a gap can create uneven loading on the retainer ring, whichmay cause misalignment of the cylinder under load. Additionally, specialtooling required for removal and installation of the ring is oftencumbersome and reduces the efficiency of service and repair processes.

In view of the above limitations of known cylinder systems, it would bedesirable to provide a means for positioning and retaining a fluidcylinder that utilized less components, did not require special toolingto install and remove from a drill casing, was simpler to manufactureand overcame the other inherent limitations of these previously knownsystems.

SUMMARY OF THE INVENTION

In one aspect, the present invention is a fluid distributor device for apercussive drill assembly, the drill assembly including a generallytubular casing having a longitudinal centerline. The distributor devicecomprises a generally cylindrical body disposeable within the casing andhaving a central axis, two opposing ends spaced apart along the axis andat least one fluid passage extending generally between the two ends. Adeflectable retainer portion of the body is configured to releasablyengage with the casing so as to locate the body at a desired positionwith respect to the centerline.

In another aspect, the present invention is also a fluid distributordevice for a percussive drill assembly, the drill assembly including agenerally tubular casing having a longitudinal centerline. Thedistributor device comprises a generally cylindrical body having firstand second interior chambers, a port fluidly connecting the first andsecond chambers, and a deflectable retainer portion configured toreleasably engage with the casing so as to retain the body at a desiredposition with respect to the casing centerline. A valve is disposedwithin the body and configured to permit fluid flow through the port andto alternatively prevent fluid flow through the port.

In a further aspect, the present invention is a percussive drillassembly comprising a casing having a longitudinal centerline and aninner circumferential surface. A piston is disposed within the casingsuch that a piston reservoir chamber is defined generally between thepiston and the casing inner surface. A distributor cylinder is disposedwithin the casing and includes a central axis generally collinear withthe casing centerline, two opposing axial ends spaced apart along theaxis, first and second interior chambers and a port fluidly connectingthe first and second chambers. The cylinder also includes at least onefluid passage extending generally between the two ends and fluidlyconnecting the first chamber with the reservoir chamber, and adeflectable retainer portion releasably engaged with the casing innersurface so as to retain the body at a desired position with respect tocasing centerline. Further, a valve is disposed within the distributorcylinder and is configured to permit fluid flow through the port and toalternatively prevent fluid flow through the port.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

The foregoing summary, as well as the detailed description of thepreferred embodiments of the invention, will be better understood whenread in conjunction with the appended drawings. For the purpose ofillustrating the invention, there is shown in the drawings, which arediagrammatic, embodiments that are presently preferred. It should beunderstood, however, that the invention is not limited to the precisearrangements and instrumentalities shown. In the drawings:

FIG. 1 is exploded view of a percussive drill assembly having adistributor device in accordance with the present invention;

FIG. 2 is a side cross-sectional view of a percussive drill having thedistributor cylinder shown in an installed position;

FIG. 3 is a broken-away, enlarged cross-sectional view of thedistributor device installed in the casing;

FIG. 4 is a side cross-sectional view of a drill casing and with thedistributor device shown spaced axially from an installed position;

FIG. 5 is a broken-away, greatly enlarged side cross-sectional view of alug of the distributor device shown engaged with a retainer recess ofthe casing;

FIG. 6 is an enlarged rear perspective view of a cylindrical body of thedistributor of the present invention.

FIG. 7 is a broken-away, greatly enlarged side cross-sectional view of avalve and shoulder of the distributor device showing the valve in anopen position.

DETAILED DESCRIPTION OF THE INVENTION

Certain terminology is used in the following description for convenienceonly and is not limiting. The words “upper”, “upward”, and “lower”,“downward” refer to directions toward and away from, respectively, adesignated upper end of a drill assembly. The words “inner”, “inward”and “outer”, “outward” refer to directions toward and away from,respectively, the geometric center of the drill assembly, the drillcenterline or the distributor body central axis, the particular meaningintended being readily apparent from the context of the description. Theterms “radial” and “radially-extending” refer to directions generallyperpendicular to a designated centerline or axis, and refer both toelements that are either partially or completely oriented in radialdirection. The terminology includes the words specifically mentionedabove, derivatives thereof, and words or similar import.

Referring now to the drawings in detail, wherein like numbers are usedto indicate like elements throughout, there is shown in FIGS. 1-6 apresently preferred embodiment of a fluid distributor device 10 for afluid-operated percussive drill assembly 1. The drill assembly 1preferably includes a source of operating fluid A (showndiagrammatically), which is preferably compressed air, a casing 2 havinga longitudinal centerline 3 and a piston 6 disposed within the casing 2such that a piston reservoir chamber 27 is defined generally between thepiston 6 and the casing 2. The distributor device 10 basically comprisesa generally cylindrical body 12 disposeable within the casing 2 andhaving a central axis 11 and first and second opposing ends 12 a, 12 b,respectively, spaced apart along the axis 11. The body 12 further has atleast one fluid passage 14 extending generally between the two ends 12a, 12 b and a deflectable retainer portion 16. The retainer portion 16is configured to releasably engage with the casing 2 to retain thecylindrical body 12 at a desired position P in the casing 2 with respectto the centerline 3. It must be noted that the desired position P isindicated by the location of a designated center point C of the body 12to facilitate description of the present invention and the particularreference center point C has been selected for convenience only.

Preferably, the distributor body 12 further has a first and secondinterior chambers 23, 25, respectively, and a primary port 48 fluidlyconnecting the first and second chambers 23 and 25. The distributordevice 10 preferably further comprises a valve 7 disposed within thebody 12 and configured to permit fluid flow through the port 48 and toalternatively prevent fluid flow through the port 48. The first or“supply” chamber 23 is fluidly connectable with the operating fluidsource A and the fluid passage 14 fluidly connects the supply chamber 23with the reservoir chamber 27 when the body 12 is located at the desiredposition P. As such, the fluid passage 14 enables operating fluid to bechanneled to a return chamber 31 (FIG. 2) to cause the piston 6 tolinearly displace in an upward, return direction 3 b along thecenterline 3, as discussed in further detail below. Further, the piston6 preferably has an upper portion 6 a disposeable within the second or“drive” interior chamber 25 such that when the valve 7 permits fluidflow through the port 48, operating fluid flows from the first, supplychamber 23 to the second or “drive” chamber 25 to cause the piston 6 tolinearly displace within the casing 2 in a downward, drive direction 3 agenerally along the casing centerline 3.

Further, the retainer portion 16 is preferably formed as a segmentedring 17 configured to deflect or collapse generally inwardly toward thebody central axis 11 and to alternatively expand generally outwardlyaway from the axis 11. More specifically, the distributor body 12preferably further includes a generally solid tubular portion 33 and theretainer segmented ring 17 is integrally attached or formed with thetubular portion 33. The segmented ring 17 preferably includes aplurality of slotted openings 18 that divide the retainer portion 16into a plurality of deflectable, cantilever-like locking arms 20. Eachlocking arm 20 has a first, inner end attached to the body tubularportion 33 and a second, outer or free end 24 engageable with the casing2 to retain the body 12 at the desired position P. Most preferably, thelocking arms 20 each have a lug 26 that engages with a retainer recess 9in the casing 2 to removably mount the distributor body 12 within thecasing 2, as described more fully below. Each of the above-discussedelements or components of the fluid distributor device 10 is describedin further detail below.

Although a detailed description of the drill assembly components isbeyond the scope of the present disclosure, certain details aredescribed herein to more clearly disclose the distributor device 10 ofthe present invention. The distributor device 10 is preferably used witha drill assembly 1 that further includes a backhead 4 attached to anupper end 2 a of the casing 2 and a bit 5 slidably disposed at leastpartially within the lower end 2 b of the casing 2. The piston 6 isslidably disposed within the casing 2 and reciprocates in first andsecond directions 3 a, 3 b, respectively, along the centerline 3. Morespecifically, the piston upper portion/end 6 a slides within the drivechamber 25 of the distributor device 10 and the piston lower end 6 brepetitively impacts against the upper end 5 a of the bit 5. Also, aguide post 8 is attached to the backhead 4, extends through and centersthe valve 7 within the distributor body 12 and has a lower end 8 a thatengages inside the piston 6.

Further, the drill casing 2 preferably further includes an innercircumferential surface 2 c and a retainer recess 9 configured to engagewith the retainer portion 16 of the distributor body 12. Specifically,the retainer portion 16 is engageable with the casing recess 9 to retainthe distributor body 12 at the desired position P and alternativelydisengageable from the casing recess 9 to permit the body 12 to bedisplaceable in a direction along the casing centerline 3. Preferably,the retainer recess 9 is generally annular and extends circumferentiallyinto the casing 2 from the inner surface 2 c and is preferably formed asa single, continuous recess circumscribing the drill centerline 3.Alternatively, the retainer recess 9 may be formed as a plurality ofseparate arcuate recess sections (not shown) spaced circumferentiallyabout the drill centerline 3. As best shown in FIG. 5, the casingretainer recess 9 preferably includes an upper, lead-in and releasesurface section 9 a that is sloped or angled so as to face generallyradially-inwardly toward the drill centerline 3, a lower, generallyradially-extending or “radial” stop surface section 9 b and a centralinner circumferential surface section 9 c disposed between the upper andlower surfaces 9 a, 9 b, respectively. The three casing recesssurfaces/surface sections 9 a, 9 b and 9 c interact with specificsurfaces of the distributor retainer portion 16, as described below.

Referring now to FIGS. 1-4 and 6, the cylindrical body 12 of thedistributor device 10 has inner and outer circumferential surfaces 13,15, respectively, and is preferably shaped so as to have “axial”cross-sections (i.e., cross-sections perpendicular to and spaced alongthe axis 11) that are substantially circular. Referring specifically toFIG. 4, the body 12 has an outside diameter D₀ that is generallyconstant along the axis 11, except at the region of the locking lugs 26.The outside diameter D₀ of the cylindrical distributor body 12 is sizedsufficiently smaller or lesser than an inside diameter D₁ of the casing2 to enable installation of the distributor device 10 into the casing 2,as described in further detail below.

As discussed above, the retainer portion 16 is preferably provided by anintegral collapsable ring 17 of the body 12 that is located at the bodyupper end 12 a. As best shown in FIG. 6, the slotted openings 18 segmentor divide the collapseable ring 17 into eight locking arms 20, which arespaced circumferentially about the central axis 11. As such, when thelocking arms 20 engage with the casing 2, as described below, thedistributor body 12 is generally centered about the casing centerline 3.Further, each slotted opening 18 extends generally axially and inwardlyfrom the first, upper end 12 a of the distributor body 12 and enlargesinto a fluid port 19. Each fluid port 19 fluidly connects a separateouter fluid passage 14 with the upper supply chamber 23, as discussed infurther detail below.

Each locking arm 20 has a first, inner end 22 integrally attached orformed with the solid tubular portion 33 of the cylindrical body 12 anda second, free end 24 located at the body upper end 12 a. The arms 20are each “bendable” or configured to bend or deflect at or about the armfirst end 22 so as to displace the arm outer end 24 generally toward thebody central axis 11 and to alternatively displace the arm outer end 24generally away from the body axis 11. In other words, the arm outer end24 is movable between a first, most distal position with respect to thecentral axis 11 (e.g., FIG. 2) and a second, most proximal position withrespect to the axis 11 (e.g., FIG. 4), for reasons described below.Further, each locking arm 20 includes a projection or lug 26 disposedproximal to, preferably spaced inwardly from, the outer, free end 24 ofthe arm 20 and extending radially outwardly from an outer surface 21 ofthe arm 20.

Referring particularly to FIG. 5, the locking lugs 26 are eachconfigured to releasably engage with, and are preferably disposablewithin, the retainer recess 9 of the casing 2 to locate and releasablyretain the distributor device 10 at a desired axial position withrespect to the drill centerline 3. Preferably, each lug 26 includes anouter circumferential surface section 28, a radially-extending or“radial” stop surface section 30 and an angled or sloped release surfacesection 32. The three lug surfaces/surface sections 28, 30 and 32interacting with the surfaces 9 a, 9 b and 9 c of the casing recess 9 inthe following manner. Each lug 26 is generally sized such that when theentire retainer portion 16 is engaged with the casing recess 9, theouter circumferential surface 28 of each lug 26 is generally disposedagainst the inner circumferential surface 9 c of the casing recess 9,the collective effect of which is to substantially center thedistributor body 12 about the drill centerline 3.

Further, when the lugs 26 are disposed in the recess 9, the lug stopsurfaces 30 are contactable with the recess stop surface 9 b to limitaxial movement of the distributor body 12 in the first, downwarddirection 3 a along the drill centerline 3. Each radially-outwardlyfacing release surface 32 is contactable with the radially-inwardlyfacing lead-in/release surface 9 a of the casing recess 9 to generallylimit axial movement in the second, upward direction 3 b along the drillcenterline 3, although the backhead 4 primarily limits distributor bodymovement in the upward direction 3 b, preferably through an intermediateelastic member 66. More specifically, an elastic member 66, such as abelleville spring, a compression cone or another appropriate component,is preferably disposed between the backhead 4 and the body 12 andfunctions both to develop an axial pre-load on the distributor device 10and to accommodate variations in manufacturing tolerance of the backhead4 and the body 12. Therefore, during normal operation of the drillassembly 1, the lugs 26 are retained within the recess 9 as the resultof contact between the backhead 4 and the body upper end 12 a (i.e.,through the elastic member 66) and by contact between the respectivelower stop surfaces 30, 9 c of the lugs 26 and casing recess 9. Theretention of the lugs 26 within the casing recess 9 locates and retainsthe distributor device 10 at the desired position P with respect to thedrill centerline 3.

However, when a sufficient force is applied to the distributor device 10generally in the second direction 3 b, the body 12 begins to displace inthe second direction 3 a such that the lug release surfaces 32 slideagainst the casing lead-in surface 9 a. The interaction between theangled surfaces 32 and 9 a deflects the locking arms 20 to bendradially-inwardly about the arm inner ends 24 such that the outer, freeends 26 displace generally inwardly toward the axial centerline 3. Theretainer portion 16 of the distributor device 10 thereby becomesinwardly collapsed to release the lugs 26 from the casing recess 9 toslide along the inner circumferential surface 2 c of the casing 2, asdepicted in FIG. 4. The distributor device 10 is then capable of beinglinearly displaced or slided along the drill centerline 3 in the second,upward direction 3 b until the body 12 is completely extracted orremoved from the casing 2.

Referring to FIGS. 2 and 6, the distributor body 12 preferably has aplurality of fluid passages 14, most preferably eight passages 14,spaced circumferentially about the body axis 11 and each configured tofluidly connect the first, supply chamber 23 with the piston reservoirchamber 27 during normal drill operation. Each fluid passage 14 ispreferably formed as an outer recess 38 extending radially-inwardly intothe body 12 from the body outer circumferential surface 15 and generallyaxially with respect to the central axis 12. Further, each axial recess38 is generally rectangular-shaped and extends between a separate one ofthe upper fluid ports 19 and the second end 12 b of the body 12. Whenthe distributor body 12 is installed in the casing 2, each fluid passage14 is partially bounded by a proximal section of the casing innercircumferential surface 2 c. Alternatively, the fluid passages 14 may beprovided by axially-extending interior holes or passages (not shown)contained or enclosed within the cylindrical distributor body 12.

As best shown in FIG. 6, four of the preferred eight recesses 38preferably include a lower fluid “blow” port 40 disposed generallyproximal to the second end 12 b of the body 12 and fluidly connectingthe particular recess 38 with the second, drive chamber 25. The blowports 40 each establish a fluid path from the upper, supply chamber 23,through the associated fluid passage 14, the particular port 40 and thelower, drive chamber 25, into the drill bore passage 29 and out thecasing 2, the fluid path functioning to relieve pressure from the drillassembly 1 when the drill 1 is non-operational. Further, the twodistributor chambers 23 and 25 are each at least partially bounded bythe inner circumferential surface 13 of the body 12 and function toappropriately direct or apply the operating fluid used to operate thedrill assembly 1, as discussed above and in further detail below.

Referring particularly to FIGS. 3, 4 and 6, the distributor body 12preferably further includes an annular shoulder 42 extending radiallyinwardly from the body inner surface 13. The annular shoulder 42preferably extends circumferentially and continuously about the bodyinner surface 13 so as to circumscribe the central axis 11. Although notpreferred, the shoulder 42 may alternatively be provided by two or morearcuate shoulder segments (not show) spaced circumferentially about thebody inner surface 13. The shoulder 42 has an inner circumferentialsurface 46 bounding the primary port 48 and a radially-extending valveseat surface 44 against which the valve 7 is disposeable, as discussedbelow.

As best shown in FIG. 3, the valve 7 is preferably formed as a generallycylindrical block 50 with a central axial bore 52, the central bore 52having an enlarged, counterbore portion 54. The valve block 50 includesa radial shoulder portion 56 having a radially-extending, annularcontact surface 58 disposeable against the shoulder seat surface 44.Further, the valve block 50 also includes a lower, circular cylindricalportion 60 with an outer circumferential surface 62. The valve lowerportion 60 is disposeable within the distributor port 48 and has anouter diameter (not indicated) that is lesser than the inner diameter(not indicated) of the body shoulder 42. As such, an annular fluidpassage 64 is formed within the primary port 48 when the valve 7 isassembled in the distributor device 10. More specifically, the annularfluid passage 64 is defined between the shoulder inner surface 46 andthe valve outer surface 62 when the valve 7 is slidably disposed on theguide post 8 of the drill assembly 1. Alternatively, the valve 7 may beformed without the lower portion 60, such that the valve contact surface58 extends completely across the lower end of the valve block 50 and theentire port 48 is used to channel or direct fluid flow between thesupply and drive chambers 23 and 25, respectively (structure not shown).

The valve 7 is displaceable with respect the distributor body 12 betweena first position (as shown in FIGS. 3 and 4) and a second position (FIG.7). In the first position, the valve shoulder surface 58 is disposedagainst the valve seat surface 44 of the shoulder 42 to substantiallyprevent fluid flow through the annular fluid passage 64. In the secondposition (FIG. 7), the valve 7 is spaced axially from the shoulder seatsurface 44 in the second direction 3 a along the drill centerline 3 soas to permit fluid flow through the annular passage 64 within the port48, and therefore between the supply and drive chambers 23 and 25,respectively. Preferably, the valve 7 moves between the first and secondpositions by action of the movement of the piston 6 in the second,return direction 3 b, which compresses operating fluid within the drivechamber 25 such that the compressed fluid forces the valve body 50 toslide upwardly upon the post 8. The opening of the valve 7 permitsoperating fluid in the supply chamber 23 to flow through the passage 64,into the drive chamber 25 and against the upper end/portion 6 a of thepiston 6, causing the piston 6 to linearly displace within the casing 2downwardly along the centerline 3 to impact with the bit 5.

Preferably, the distributor body 12 of the present invention is machinedfrom a tube of a hot-rolled metallic material, most preferably 4140steel, and the valve 7 is machined from a bar of a polymeric material,most preferably acetyl. However, the distributor device 10 of thepresent invention is not limited to being constructed from anyparticular type of material and/or fabrication method. For example, thebody 12 and/or valve 7 may be made of iron, ceramic or a polymericmaterial and/or may be made by any appropriate fabrication method, suchas for example, casting or forging.

Referring now to FIGS. 1-5, the distributor device 10 is assembled intothe casing 2 in the following manner. The second or lower end 12 b ofthe cylindrical body 12 is inserted into the upper end 2 a of the casing2 and the body 12 is then “pushed” so as to displace along the drillcenterline 3 in the first or downward direction 3 a. The outercircumferential surface 15 of the body 12 slides against the innercircumferential surface 2 c of the casing 2 until the locking lugs 26contact the upper end 2 a of the casing 2. Then, a radially-inwardlydirected force is applied to the distributor retainer portion 16 tocause the locking arms 20 to collapse or bend radially-inwardly towardthe drill centerline 3 to a collapsed configuration, as depicted in FIG.4. The locking arms 20 must bend sufficiently to displace the lugs 26inwardly by an adequate radial distance to enable the lugs 26 to enterthe interior of the casing 2 through the casing first end 2 a.

As shown in FIG. 4, the lug outer surfaces 28 then slide against thecasing inner surface 2 c, along with the remainder of the body outersurface 15, as the body 12 displaces along the axis 3 until the lugs 26reach the casing recess 9. The lugs 26 then “snap” or displaceradially-outwardly into the casing recess 9 (as shown in FIG. 5) byaction of elastic material forces stored in each of the bendedcantilever-like locking arms 20. The body 12 is then displaced anadditional, relatively short distance along the centerline 3 in thefirst direction 3 b until the lug radial stop surface 30 contacts thecasing radial stop surface 9 b, such that the distributor device 10 ispositioned or located at the desired position P. Next, the elasticmember 66 is placed against the first, upper end 12 a of the body 12 andthen the backhead 4 of the drill assembly 1 is attached or threaded ontothe upper end 2 a of the casing 2, such that a downwardly-facing radialsurface 4 a of the backhead 4 compresses the elastic member 66 againstthe body first end 12 a. The backhead 4 thereby limits movement of thedistributor body 12 in the first or upper direction 3 a and thusprevents the lugs 26 from sliding out of the casing recess 9.

Thereafter, the distributor device 10 is retained at a specific positionon or with respect to the drill centerline 3, with the body central axis11 being substantially collinear with the centerline 3. The distributorbody 12 remains substantially stationary at the desired position P untilit is desired to remove the distributor device 10 from the casing 2,which is accomplished by releasing the lugs 26 from the casing recess 9as described above.

The distributor device 10 of the present invention is clearlyadvantageous compared with previously known distributor devices, such asthose discussed in the Background section of this disclosure. First, thedistributor body 12 is retained in a specific position in the casing 2without the need for additional mounting or retaining components, suchas a separate retaining ring or ring segments. Further, thecircumferentially spaced lugs 26 contact the casing recess 9 in a mannersuch that the forces applied by the retainer portion 16 are evenlydistributed, thereby preventing any loading imbalance such as occurswith split-ring type retaining devices, as described above. Furthermore,by eliminating the separate ring or ring segments, the need for specialtools or fixtures generally required to assemble a cylinder and ringassembly is also eliminated. In addition, the incorporation of the valve7 into the distributor device 10 eliminates certain valve componentsrequired with other fluid distributor systems.

It will be appreciated by those skilled in the art that changes could bemade to the embodiments described above without departing from the broadinventive concept thereof. It is understood, therefore, that thisinvention is not limited to the particular embodiments disclosed, but itis intended to cover all modifications within the spirit and scope ofthe present invention as described and depicted herein.

1. A fluid distributor device for a percussive drill assembly, the drillassembly including a generally tubular casing having a longitudinalcenterline, the distributor device comprising: a generally cylindricalbody disposeable within the casing and having a central axis, twoopposing ends spaced apart along the axis, at least one fluid passageextending generally between the two ends, and a deflectable retainerportion configured to releasably engage with the casing so as to locatethe body at a desired position with respect to the centerline.
 2. Thedistributor device as recited in claim 1 wherein: the drill assemblyfurther includes a source of operating fluid and a piston, the pistonbeing disposed within the casing such that a reservoir chamber isdefined generally between the piston and the casing; and the bodyfurther has an interior supply chamber, the supply chamber being fluidlyconnectable with the operating fluid source and the fluid passagefluidly connecting the supply chamber and the reservoir chamber when thebody is located at the desired position.
 3. The distributor device asrecited in claim 1 wherein: the body further has first and secondinterior chambers and a port fluidly connecting the first and secondchambers; and the distributor device further comprises a valve disposedwithin the body and configured to permit fluid flow through the port andto alternatively prevent fluid flow through the port.
 4. The distributordevice as recited in claim 3 wherein: the drill assembly furtherincludes a piston, the piston being disposed within the casing andhaving a portion disposeable within the body second chamber, and asource of operating fluid connected with the casing; and the body firstchamber is fluidly connectable with the operating fluid source such thatwhen the piston portion is disposed within the body second chamber andthe valve permits fluid flow through the port, operating fluid flowsfrom the first chamber into the second chamber to cause the piston tolinearly displace within the casing in a direction generally along thecasing centerline.
 5. The distributor device as recited in claim 3wherein: the distributor body further has an inner circumferentialsurface and an annular shoulder extending radially inwardly from theinner surface and circumferentially about the central axis, the shoulderhaving an inner circumferential surface bounding the port and aradially-extending valve seat surface; and the valve is movable betweena first valve position where the valve where the valve is disposedagainst the seat surface so as to prevent fluid flow through the portand a second valve position is spaced from the seat surface so as topermit fluid flow through the port.
 6. The distributor device as recitedin claim 5 wherein the drill assembly further includes a backhead havinga post, the post being disposed at least partially within thedistributor body, the valve being disposeable upon the post so as toslidably displace between the first and second valve positions.
 7. Thedistributor device as recited in claim 1 wherein: the casing furtherincludes an inner circumferential surface and a generally annular recessextending circumferentially into the casing from the inner surface; andthe retainer portion is engageable with the casing recess to retain thedistributor body at the desired position and alternatively disengageablefrom the casing recess to permit the body to be displaceable in adirection along the casing centerline.
 8. The distributor device asrecited in claim 1 wherein the retainer portion is formed as a segmentedring configured to collapse generally inwardly toward the body centralaxis and to alternatively expand generally away from the axis.
 9. Thedistributor device as recited in claim 1 wherein the distributor bodyfurther includes a generally solid tubular portion, the retainingportion being integrally formed with the tubular portion and including aplurality of deflectable locking arms, each locking arm having an innerend attached to the tubular portion and an outer, free end engageablewith the casing to retain the body at the desired position.
 10. Thedistributor device as recited in claim 9 wherein each locking arm isbendable generally about the arm inner end so as to displace the armouter end generally toward the body central axis and to alternativelydisplace the arm outer end generally away from the body axis.
 11. Thedistributor device as recited in claim 9 wherein the plurality oflocking arms are spaced circumferentially about the body axis such thatwhen the arms engage with the casing, the distributor body is generallycentered about the casing centerline.
 12. The distributor device asrecited in claim 9 wherein: the casing further includes an innercircumferential surface and a generally annular recess extendingcircumferentially into the casing from the inner surface; and eachlocking arm includes a lug disposed proximal to the arm outer end anddisposeable within the casing recess so as to retain the distributorbody at the desired position.
 13. The distributor device as recited inclaim 12 wherein: the casing recess has a generally radial surfacesection and an angled surface section; and each lug includes a generallyradial surface section contactable with the recess radial surfacesection when the distributor body is displaced in a first directionalong the casing centerline so as to locate the body at the desiredposition and an angled surface section slidable against the recessangled surface section so as to deflect the arm inwardly toward thecentral axis when the body is displaced in a second, opposing directionto release the lug from the recess such that the body is furtherdisplaceable within the casing in the second direction.
 14. Thedistributor device as recited in claim 1 wherein the distributor bodyfurther has an outer circumferential surface and the fluid passage isformed as an outer recess extending into the body from the outer surfaceand generally axially with respect to the central axis.
 15. Thedistributor device as recited in claim 14 wherein the distributor bodyhas a plurality of the fluid passage recesses spaced circumferentiallyabout the central axis.
 16. A fluid distributor device for a percussivedrill assembly, the drill assembly including a generally tubular casinghaving a longitudinal centerline, the distributor device comprising: agenerally cylindrical body having first and second interior chambers, aport fluidly connecting the first and second chambers, and a deflectableretainer portion configured to releasably engage with the casing so asto retain the body at a desired position with respect to the casingcenterline; and a valve disposed within the body and configured topermit fluid flow through the port and to alternatively prevent fluidflow through the port.
 17. The distributor device as recited in claim 16wherein the body further has a central axis, two opposing ends spacedapart along the axis and at least one fluid passage extending generallybetween the two ends.
 18. The distributor device as recited in claim 17wherein: the drill assembly further includes a piston disposed withinthe casing such that a reservoir chamber is defined generally betweenthe piston and the casing; and the fluid passage fluidly connects thefirst chamber and the reservoir chamber when the body is located at thedesired position.
 19. The distributor device as recited in claim 17wherein the distributor body further has an outer circumferentialsurface and the fluid passage is formed as a recess extending into thebody from the outer surface and generally axially with respect to thecentral axis.
 20. The distributor device as recited in claim 19 whereinthe distributor body has a plurality of the fluid passage recessesspaced circumferentially about the central axis.
 21. The distributordevice as recited in claim 16 wherein: the drill assembly furtherincludes a piston, the piston being disposed within the casing andhaving a portion disposeable at least partially within the body secondchamber, and a source of operating fluid; and the body first chamber isfluidly connectable with the operating fluid source such that when thepiston head is disposed within the body second chamber and the valvepermits fluid flow through the port, operating fluid flows from thefirst chamber into the second chamber to cause the piston to linearlydisplace within the casing in a direction generally along the casingcenterline.
 22. The distributor device as recited in claim 16 wherein:the body further has an inner circumferential surface and an annularshoulder extending radially inwardly from the inner surface andcircumferentially about the central axis, the shoulder having an innercircumferential surface defining the port and a radially-extending valveseat surface; and the valve is movable between a first valve positionwhere the valve is disposed against the seat surface so as to preventfluid flow through the port and a second valve position where the valveis spaced from the seat surface so as to permit fluid flow through theport.
 23. The distributor device as recited in claim 16 wherein: thecasing further includes an inner circumferential surface and a generallyannular recess extending circumferentially into the casing from theinner surface; and the retainer portion is engageable with the casingrecess to retain the distributor body at the desired position andalternatively disengageable from the casing recess to permit the body tobe displaceable in a direction along the casing centerline.
 24. Thedistributor device as recited in claim 16 wherein the distributor bodyfurther includes a generally solid tubular portion, the retainingportion being integrally formed with the tubular portion and including aplurality of deflectable locking arms, each locking arm having an innerend attached to the tubular portion and an outer, free end engageablewith the casing to retain the body at the desired position.
 25. Thedistributor device as recited in claim 24 wherein the plurality oflocking arms are spaced circumferentially about the body axis such thatwhen the arms engage with the casing, the distributor body is generallycentered about the casing centerline.
 26. The distributor device asrecited in claim 24 wherein: the casing further includes an innercircumferential surface and a generally annular recess extendingcircumferentially into the casing from the inner surface; and eachlocking arm includes a lug disposed proximal to the arm outer end anddisposeable within the casing recess so as to retain the distributorbody at the desired position.
 27. A percussive drill assemblycomprising: a casing having a longitudinal centerline and an innercircumferential surface; a piston disposed within the casing such that apiston reservoir chamber is defined generally between the piston and thecasing inner surface; a distributor cylinder disposed within the casingand including a central axis generally collinear with the casingcenterline, two opposing axial ends spaced apart along the axis, firstand second interior chambers, a port fluidly connecting the first andsecond chambers, at least one fluid passage extending generally betweenthe two ends and fluidly connecting the first chamber with the reservoirchamber, and a deflectable retainer portion releasably engaged with thecasing inner surface so as to retain the body at a desired position withrespect to casing centerline; and a valve disposed within thedistributor cylinder and configured to permit fluid flow through theport and to alternatively prevent fluid flow through the port.